Certain metals have been known to include anti-microbial properties. These anti-microbial properties are ideal for use in materials having a sustained efficacy against bacteria. Exemplary metals having anti-microbial properties include, for example, silver, copper, zinc, gold, platinum, and palladium.
In the past, silver has been used in the food service industry and for home use, for example in goblets and silverware, because it is believed to inhibit diseases. In particular, colloidal silver is thought to be useful as a strong, natural antibiotic, and for prevention of infections. Without being limited to theory, it is believed that the high particle surface area of colloidal silver enables high bioavailability for maximum effectiveness. Colloidal silver has been found effective against germs, bacteria, infections, parasites, viruses, fungus and pathogens. In addition, colloidal silver has an infinite shelf life. When colloidal silver is in proximity to a virus, fungus, bacterium, or any other single-celled pathogen, it acts as a catalyst to disable the oxygen metabolism enzyme without incurring harm to human enzymes or the human body's chemistry. Thus colloidal silver is safe for humans, animals, plants, and all multi-celled living mater.
Silver has been successfully used in treating more than 650 diseases. A non-limiting list of treated conditions includes acne, AIDS, allergies, appendicitis, arthritis, athlete's foot, tuberculosis, bladder inflammation, blood parasites, blood poisoning, boils, bubonic plague, burns, cancer, candida, chilblains, cholera, colitis, conjunctivitis, cystitis, diabetes, dysentery, eczema, fibrositis, gastritis, gonorrhea, hay fever, herpes, impetigo, indigestion, keratitis, leprosy, leukemia, lupus, lymphangitis, lyme disease, malaria, meningitis, neurasthenia, parasitic infections both viral and fungal, pneumonia, pleurisy, prostate, psoriasis, purulent ophthalmia, rhinitis, rheumatism, ringworm, scarlet fever, septic conditions of the eyes, ears, mouth and throat, seborrhea, septicemia, shingles, skin cancer, staph infections, strep infections, syphilis, thyroid, tonsillitis, toxemia, trachoma, trenchfoot, dermatitis, all forms of virus, wars, whooping cough, yeast infection, stomach ulcer, and also canine parvovirus and other veterinary uses.
In addition, colloidal silver is effective for severe acute respiratory syndrome (SARS) which is caused by SARS coronavirus. Also, certain disinfectants are known and include ethanol, sodium hypochlorite, iodophor, peracetic acid, formaldehyde, glutaraldehyde and ethylene oxide gas. However, these disinfectants are only temporary and only effective with a direct application to the disinfecting site. Thus, these disinfectants are not suitable for sustained effectiveness.
A major challenge facing the pharmaceutical industry is how to cope with increasing drug resistance of pathogens to commercially available drugs in view of mutation of chromosomal genes. By way of example, each year, nearly 9 million people develop tuberculosis, of which about two million will die. The emergence and spread of multidrug-resistant (MDR) Mycobacterium Tuberculosis (MT) represents a worldwide healthcare problem because of the difficulty in treating these infections.
It has been demonstrated that colloidal silver does not interact or interfere with other medicines being taken by a patient. More specifically, colloidal silver does not form toxic compounds or react with anything other than a germ's oxygen-metabolizing enzyme. Thus, it follows that no tolerance to colloidal silver will develop through mutation. The high particle surface area can enable high bioavailability for maximum effectiveness. It is the discovery of the inventors that high particle surface area can be obtained in a nanosilver product.
Currently, almost all nanosilver products are found in water or organic solvent such as dimethylformamide (DMF), dimethylacetamide (DMAC), ethylene glycol (EG), and glycerine as colloids. Silver colloid particles having narrow size distribution are manufactured by electrolysis, reducing agents such as hydrazine, NaBH4, LiAlBH4, or by radiation exposure. The manufactured silver corpuscles are collected by a centrifugal separator, and then dispersed again in the original medium. A particle of nano size always forms an oxidized film on a surface thereof when it is exposed to air. An antioxidant such as butylhydroxy toluene and vitamin E derivative are used to prevent oxidation of a surface formed of metal particles. The nano size particles tend to agglomerate due to a tendency of each particle to minimize its surface area. Accordingly, it is difficult to obtain separated nano particles. In an effort to maintain separate particles, surface active agents can be used. Examples of these surface active agents can include sodium dodecyl sulfate, polyvinyl alcohol, and polyvinylpyrollidone. The additives block growth of the composite metal particles, and thereby keep the particle at a nano size.
In order to maintain a resistance to high temperatures, silver based inorganic anti-microbial agents can comprise silver carried on an inorganic compound. A carrier which stably holds the silver nanoparticles can include active charcoal (JP Patent Publication No. 49-61950), soluble glass (JP Patent Publication No. 63-181002), zirconium phosphate (JP Patent Publication No. 3-83905), apatite, silica, titanium oxide, porous ceramics, and titanium. As an antibacterial agent, nanosilver can be distributed in the vicinity of the surface of a resin material. The resultant composition can exhibit antibacterial properties, mildew resistance, permanence of mildew resistance and weatherability such as heat resistance and ultraviolet light resistance.
Another method for combining silver and silica can be found in DE 96 50 500A1 in which a one-step pyrogenic silica doping is modified and a process is disclosed for preparation of pyrogenic silica doped with silver or silver oxide. The doping process differs from a previous “co-fumed” process in which gaseous starting materials (for example SiCl4 vapor and AlCl3 vapor) are premixed and burnt together in a flame reactor. The silver salt/water aerosol produced in the aerosol generator is passed through a heating zone with a light carrier gas stream. The aerosol is mixed homogeneously with SiCl4 vapor and H2, and O2 mixture used for the flame oxidation or the flame hydrolysis before the reaction. Then, the aerosol/gas mixture is reacted in the flame and the resulting pyrogenically prepared silicas doped with silver or silver oxide are separated from the gas stream.
As a source for silver growth, however, flame oxidation and flame hydrolysis are far different at a high temperature. The multiple-phase, multi-reaction, high temperature process is too complicated for scale-up and a large financial investment is needed. Further, the nano size of the silver particles is difficult if not impossible to maintain due to their quick reduction, nucleation, agglomeration and the difficulty in controlling Ag crystalline growth at high temperatures. Because of these and other difficulties, the silver distribution is non-uniform, resulting in reduced drug efficiency and reduced bioavailability. Similarly, embedded silver in fumed silica is less available because the fumed silica is less soluble. In addition, there is a severe corrosion problem and HCl residue still adhering to the silica will need to be removed at elevated temperatures, resulting in further growth of silver crystallites.
It would be desirable, therefore, and a need exists in the art, to utilize the benefits of colloidal silver in a form that presents a high particle surface area, which is reproducible, convenient for transportation, storage, and dispensation with required dosage, thermally stable, having an elongated disinfection time, and a long shelf life.